Bisphenoxy fluorenes are finding increasing favor as monomers from which to prepare polycarbonate because the resulting polycarbonate typically exhibits a desirably high resistance to thermal deformation and degradation. A bisphenoxy fluorene can be used alone to make a homopolycarbonate, or can be reacted together with one or more other dihydroxy compounds to make a copolycarbonate. It has been found, however, that when polycarbonate is being produced even in part from a bisphenoxy fluorene, various refinements of the typical interfacial process are desirable if production on a commercially meaningful scale is to occur.
When polycarbonate is prepared from Bisphenol-A, which is the monomer most widely used in commercial production, the reaction between Bisphenol-A and a carbonate precursor typically occurs at a temperature in the range of about 25.degree.-40.degree. C., and complete dissolution of Bisphenol-A in the aqueous phase of the reaction mixture may be easily obtained at that temperature. However, a bisphenoxy fluorene is not soluble to any significant degree in aqueous base at a temperature in the range which is ordinarily associated with the production of Bisphenol-A polycarbonate. At a temperature of less than 50.degree. C., for example, a mixture of aqueous base and a bisphenoxy fluorene at a concentration of above 0.05M has the consistency of a viscous paste. It is not practical, from the standpoint of material flow and handling, to utilize a reaction mixture for production of polycarbonate from a bisphenoxy fluorene on a plant scale if the bisphenoxy fluorene is not at least substantially completely dissolved in the aqueous phase thereof.
In Report AD-777 731 to the Naval Air Systems Command (January 1974), Kambour and Niznik describe the interfacial formation of polycarbonate from a bisphenoxy fluorene in which it was found that the monosodium salt of a bisphenoxy fluorene is insoluble in water and organic solvents. Morgan, U.S. Pat. No.3,546,165 reports a similar problem with low solubility of a bisphenoxy fluorene in water, and, as a consequence, discloses a process for preparing polycarbonate from a bisphenoxy fluorene in which an accelerator (i.e. a phase transfer catalyst) and a 100 percent excess of base are used. In Japanese Kokai Publication 62-12,282 (1987), a process for preparing polycarbonate is set forth in which, although a bisphenoxy fluorene is reacted with phosgene dimer at a temperature of 0.degree. C.-90.degree. C., this reaction is also carried out in the presence of a surfactant (i.e. a phase transfer catalyst). Since it is usually preferred to prepare polycarbonate from a bisphenoxy fluorene by means of an interfacial process in which the bisphenoxy fluorene is soluble in the aqueous phase of the reaction mixture, a desirable improvement thereto would be a process in which not only is the bisphenoxy fluorene soluble but a phase transfer catalyst is not needed.